Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 43 7 2014 07 15 857 66 Li Qi 1. Chongqing Municipal Center for Disease Control and Prevention, Chongqing, China ; 2. Dept. of Military Epidemiology, Third Military Medical University, Chongqing, China. Xiaoling Qi 1. Chongqing Municipal Center for Disease Control and Prevention, Chongqing, China. Hongyan Xiong 1. Chongqing Municipal Center for Disease Control and Prevention, Chongqing, China. Qin Liu 1. Chongqing Municipal Center for Disease Control and Prevention, Chongqing, China. Jinxin Li 1. Chongqing Municipal Center for Disease Control and Prevention, Chongqing, China. Yao Zhang 1. Chongqing Municipal Center for Disease Control and Prevention, Chongqing, China. Xiangyu Ma 1. Chongqing Municipal Center for Disease Control and Prevention, Chongqing, China. Na Wu 1. Chongqing Municipal Center for Disease Control and Prevention, Chongqing, China. Qingyun Liu 1. Chongqing Municipal Center for Disease Control and Prevention, Chongqing, China. Liangui Feng 1. Chongqing Municipal Center for Disease Control and Prevention, Chongqing, China. 2015 10 15 Epidemiology studies have demonstrated inconsistent associations between type 2 diabetes mellitus and the risk of malignant melanoma. To this end, the aim was to perform a meta-analysis of cohort studies.Medline, PubMed, Embase and the Cochrane Library were searched up to February 2014. Cohort studies addressing the relative risk of type 2 diabetes mellitus on malignant melanoma were included in this meta-analysis. The Newcastle-Ottawa Scale was applied for quality evaluation. The pooled relative risks with the corresponding 95% confidence intervals (95% CIs) were calculated by using random-effects or random-effects model. Heterogeneity and publication bias were evaluated by I (2) and funnel plot analysis, respectively. Data was analyzed using STATA 11.0.A total of 9 independent cohorts from 8 manuscripts were entered this meta-analysis. Type 2 diabetes mellitus was slightly associated with an increased risk of malignant melanoma, and the pooled relative risk was 1.15 (95% CI, 1.00-1.32) in diabetes compared with non-diabetes with significant evidence of heterogeneity among these studies (P=0.016, I (2) =57.6%). For the studies adjusted for age, gender and obesity, the relative risks were 1.21 (95% CI, 1.03-1.42), 1.17 (95% CI, 1.01-1.35) and 1.11 (95% CI, 1.00-1.24), respectively. For the population-based studies in which case cohort established, the relative risk was 1.85 (95% CI, 1.31-2.62).Type 2 diabetes might be an independent risk factor for malignant melanoma. Further studies are needed to specifically test the effect, and fully elucidate the underlying pathophysiologic mechanisms. https://ijph.tums.ac.ir/index.php/ijph/article/view/4016 https://ijph.tums.ac.ir/index.php/ijph/article/download/4016/3675